1. Field of the Invention
The present invention relates to a plasma processing apparatus, and more particularly, to an apparatus for performing plasma processing for thin film deposits, surface treatment, etching, etc. to be performed during a process of production of semiconductor devices, liquid crystal display devices, etc.
2. Description of Prior Art
There is a plasma processing apparatus which generates plasma by an electromagnetic wave generated in an electromagnetic wave oscillator, particularly a microwave generator, introducing it into a plasma generating chamber through a window of a dielectric by a wave guide, and exciting molecules of processed gas supplied into the plasma generating chamber. In the tube wall of the wave guide in contact with the plasma generating chamber, a plurality of holes for introducing the microwave into the plasma generating chamber are formed.
Plasma is generated in the plasma chamber after the microwave is introduced. The radiated amount of electromagnetic wave energy from respective holes are equalized, in order to make plasma of a uniform distribution generated within the plasma generating chamber, for example, by forming beforehand the area of a hole on the terminal end side of the wave guide larger than those of the other holes, thereby controlling so that the radiated amount of the electromagnetic wave energy from respective holes may not become uneven by reflection of the electromagnetic wave on the terminal end side of the wave guide (e.g., see Patent Document 1).                [Patent Document 1] Japanese Patent Appln. Public Disclosure No. 8-111297 Official Gazette (pp. 2-6 and FIG. 2)        
Actually, however, even if the electromagnetic wave from the respective holes are equally radiated, there still remained a problem that the plasma distribution within the plasma generating chamber was not uniform. This was because the plasma density around the center of the plasma generating chamber and the plasma density in the neighborhood of its chamber wall were not equal, and because the extent of variation in the radiated amount of the electromagnetic wave energy from respective holes are different according to the kinds of gas introduced into the plasma generating chamber.
In the neighborhood of the plasma generating chamber wall, the amount of extinction of plasma is great for the amount of generation of plasma, and the plasma density is low, which causes a dispersion in plasma density in the plasma generating chamber. Also, the extent of this dispersion is changed by the radiated amount of electromagnetic wave energy from respective holes depending on the kinds of introduced gas elements.
To solve this problem, it was necessary to prepare a chamber having a specific shape capable of dissolving the dispersion in plasma density within the plasma generating chamber or a plurality of specific chambers adapted to the kinds of introduced gas elements.